Eye gaze boards (also known as eye transfer boards or E-tran boards) or eye gaze keyboards (e.g., a digital keyboard) are a common communication solution for people with Amyotrophic Lateral Sclerosis (ALS), or who otherwise have very limited movement but have volitional eye movements. ALS is a neurodegenerative disease that causes atrophy of motor neurons leading to the loss of muscle movement. The muscles that control eye movement are usually spared until the final stages of the disease. Thus, eye gaze boards enable communication for individuals with ALS or the like until the late stages of the disease.
High technology gaze recognition systems can also be dwell-based systems (i.e., the user dwells their gaze on a key for a period, typically several hundred milliseconds, in order to select the key). Specialized hardware set-ups can be used in eye gaze tracking systems such as head-mounted eye trackers that keep the eyes and the camera close and relatively static during head movement. Still other high-tech systems can mount a camera on a computer monitor and find pupil locations based on reflections. Unfortunately, these and other high-tech eye gaze keyboards have several problems: (1) the hardware for commercial gaze-operated keyboards is relatively expensive ($500˜$3,000 U.S. dollars); (2) the eye tracker requires calibration before each use; (3) the eye tracker does not work in certain conditions that interfere with infrared light, such as outdoors; and (4) the system requires a stand to keep it relatively static with respect to the patient, which makes it difficult to use in certain situations such as in a car or in bed. Notably, there are no eye trackers for a mobile device, and no eye trackers that are integrated into a mobile device.
Eye-gaze transfer (“E-tran”) boards are an alternative, low-tech solution to the commercial gaze-operated keyboards. An E-tran board typically is printed on a transparent plastic board. A typical configuration for an E-tran board has, for example, 8 quadrants spaced around a hole in the center of the board. Each quadrant has, for example, six letters in it. A communication partner holds up the board to face the patient (e.g., a person with ALS) while the communication partner observes the patient through the hole in the center of the board. A person with ALS can communicate using an E-tran board by focusing gaze on selected characters on a translucent board, and a communication partner (e.g., a caregiver or an interpreter) interprets the gaze. Selection of a letter, for example, is performed by two gazes. The first gaze indicates the quadrant, and the second gaze indicates the position of the letter within the indicated quadrant. The communication partner interprets each eye-gaze and can confirm the patient's selection for each eye-gaze (e.g., by having the patient blink or stare at the center of the board). Other low-tech systems rely upon the user (e.g., individual with ALS) having the ability to move a mouse, for example, or lack calibration to a particular device, user, and/or lighting condition.
E-tran boards have several drawbacks: (1) their cost is relatively low compared to gaze-tracking systems, but is not negligible (˜100 U.S. dollars); (2) the large plastic board (e.g., ˜35 cm by ˜45 cm) is not easily portable; (3) patients need to perform two eye gazes to enter one character, which can require more than 8 seconds including additional time to correct any mistakes; and (4) are challenging to master. Communication partners find gaze interpretation has a high learning curve, as they have to decode and remember entered characters and predict words. Furthermore, they provide relatively slow communication rates.
Thus, current eye-tracking input systems for people with ALS or other motor impairments are expensive, not robust under various light conditions (e.g., in sunlight or low light), and require frequent re-calibration and substantial, relatively immobile setups.